Civil Engineering Reference
In-Depth Information
Tension members
2.1Introduction
Concentricallyloadeduniformtensionmembersareperhapsthesimpleststructural
elements, as they are nominally in a state of uniform axial stress. Because of this,
theirload-deformationbehaviourverycloselyparallelsthestress-strainbehaviour
of structural steel obtained from the results of tensile tests (see Section 1.3.1).
Thus a member remains essentially linear and elastic until the general yield load
is approached, even if it has residual stresses and initial crookedness.
However, in many cases a tension member is not loaded or connected concen-
trically or it has transverse loads acting, resulting in bending actions as well as
an axial tension action. Simple design procedures are available which enable the
bending actions in some members with eccentric connections to be ignored, but
more generally special account must be taken of the bending action in design.
Tension members often have comparatively high average stresses, and in some
casestheeffectsoflocalstressconcentrationsmaybesignificant,especiallywhen
thereisapossibilitythatthesteelmaterialmaynotactinaductilefashion.Insuch
cases,thecausesofstressconcentrationsshouldbeminimised,andthemaximum
local stresses should be estimated and accounted for.
Inthischapter,thebehaviouranddesignofsteeltensionmembersarediscussed.
Thecaseofconcentricallyloadedmembersisdealtwithfirst,andthenaprocedure
whichallowsthesimpledesignofsomeeccentricallyconnectedtensionmembers
is presented.The design of tension members with eccentric or transverse loads is
then considered, the effects of stress concentrations are discussed, and finally the
design of tension members according to EC3 is dealt with.
2.2 Concentrically loaded tension members
2.2.1 Members without holes
The straight concentrically loaded steel tension member of length
L
and constant
cross-sectionalarea
A
whichisshowninFigure2.1ahasnoholesandisfreefrom
residual stress.The axial extension
e
of the member varies with the load
N
in the
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